1. Field of the Invention
The present invention relates generally to the treatment of anatomical tissue with high intensity focused ultrasound energy and, more particularly, to focused ultrasound ablation devices by which lesions of selected sizes and/or configurations are formed in anatomical tissue and to methods of thermal ablation using the same.
2. Brief Description of the Related Art
When high intensity ultrasound energy is applied to anatomical tissue, significant physiological effects may be produced in the anatomical tissue resulting from thermal and/or mechanical changes or effects in the tissue. Thermal effects include heating of the anatomical tissue; and, when the tissue is heated to a sufficiently high temperature, tissue damage such as coagulative necrosis is produced. In order to produce thermal effects in anatomical tissue, ultrasound emitting members such as transducers have been used to emit ultrasound energy which is applied to anatomical tissue by positioning the ultrasound emitting members adjacent or in contact with the tissue or by coupling the ultrasound emitting members to the tissue via an acoustic coupling medium. By focusing the ultrasound energy at one or more specific focusing zones within the tissue, thermal effects can be confined to a defined location, region, volume or area, and such location, region, volume or area can be remote from the ultrasound emitting member.
With the use of high intensity focused ultrasound (HIFU), one or more focusing zones at or within a designated target location, region, volume or area within a larger mass, body or area of anatomical tissue can be subjected to high intensity ultrasound energy while tissue surrounding the target area is subjected to much lower intensity ultrasound energy. In this manner, tissue at the target area can be heated to a sufficiently high temperature so as to cause a desired thermal effect such as tissue damage, ablation, coagulation, denaturation, destruction or necrosis while tissue surrounding the target area is not heated to damaging temperatures and, therefore, is preserved. Heating of tissue at a target location, volume, region or area to an ablative temperature creates an ablative lesion in the tissue at the target location, volume, region or area that is desirable in the treatment of various medical conditions, disorders or diseases. For example, the lesion may remain as tissue having altered characteristics or may be naturally degraded and absorbed by the patient""s body and thusly eliminated such that the remaining body, mass or area of tissue is of smaller volume or size due to the absence of the ablated tissue.
The use of high intensity focused ultrasound to eliminate tissue or to alter the characteristics of tissue at a target location, volume, region or area within a larger mass, body or area of anatomical tissue presents many advantages including minimization of trauma and pain for the patient, elimination of the need for a surgical incision, stitches and exposure of internal tissue, avoidance of damage to tissue other than that which is to be treated, altered or removed, lack of a harmful cumulative effect from the ultrasound energy on the surrounding non-target tissue, reduction in treatment costs, elimination of the need in many cases for general anesthesia, reduction of the risk of infection and other complications, avoidance of blood loss, and the ability for high intensity focused ultrasound procedures to be performed in non-hospital sites and/or on an out-patient basis.
Various ultrasound treatment devices and/or methods for treating anatomical tissue with ultrasound have been proposed as represented by U.S. Pat. No. Re. 33,590 to Dory, U.S. Pat. No. 3,990,452 to Murry et al, U.S. Pat. No. 4,658,828 to Dory, U.S. Pat. No. 4,807,633 to Fry, U.S. Pat. No. 4,858,613 to Fry et al, U.S. Pat. No. 4,951,653 to Fry et al, U.S. Pat. No. 4,955,365 to Fry et al, U.S. Pat. No. 5,033,456 to Pell et al, U.S. Pat. No. 5,036,855 to Fry et al, U.S. Pat. No. 5,054,470 to Fry et al, U.S. Pat. No. 5,065,761 to Pell, U.S. Pat. No. 5,080,101 to Dory, U.S. Pat. No. 5,080,102 to Dory, U.S. Pat. No. 5,117,832 to Sanghvi et al, U.S. Pat. No. 5,134,988 to Pell et al, U.S. Pat. No. 5,143,074 to Dory, U.S. Pat. No. 5,150,711 to Dory, U.S. Pat. No. 5,150,712 to Dory, U.S. Pat. No. 5,158,070 to Dory, U.S. Pat. No. 5,222,501 to Ideker et al, U.S. Pat. No. 5,267,954 to Nita, U.S. Pat. No. 5,269,291 to Carter, U.S. Pat. No. 5,269,297 to Weng et al, U.S. Pat. No. 5,295,484 to Marcus et al, U.S. Pat. No. 5,304,115 to Pflueger et al, U.S. Pat. No. 5,312,328 to Nita et al, U.S. Pat. No. 5,318,014 to Carter, U.S. Pat. No. 5,342,292 to Nita et al, U.S. Pat. No. 5,354,258 to Dory, U.S. Pat. No. 5,380,274 to Nita, U.S. Pat. No. 5,391,197 to Burdette et al, U.S. Pat. No. 5,397,301 to Pflueger et al, U.S. Pat. No. 5,409,002 to Pell, U.S. Pat. No. 5,417,672 to Nita et al, U.S. Pat. No. 5,431,621 to Dory, U.S. Pat. No. 5,431,663 to Carter, U.S. Pat. No. 5,447,509 to Mills et al, U.S. Pat. No. 5,474,530 to Passafaro et al, U.S. Pat. No. 5,492,126 to Hennige et al, U.S. Pat. No. 5,501,655 to Rolt et al, U.S. Pat. No. 5,520,188 to Hennige et al, U.S. Pat. No. 5,542,917 to Nita et al, U.S. Pat. No. 5,620,479 to Diederich, U.S. Pat. No. 5,676,692 to Sanghvi et al, U.S. Pat. No. 5,728,094 to Edwards, U.S. Pat. No. 5,730,719 to Edwards, U.S. Pat. No. 5,733,315 to Burdette et al, U.S. Pat. No. 5,735,280 to Sherman et al, U.S. Pat. No. 5,738,114 to Edwards, U.S. Pat. No. 5,746,224 to Edwards, U.S. Pat. No. 5,762,066 to Law et al, U.S. Pat. No. 5,800,379 to Edwards, U.S. Pat. No. 5,800,429 to Edwards, U.S. Pat. No. 5,800,482 to Pomeranz et al, U.S. Pat. No. 5,807,308 to Edwards, U.S. Pat. No. 5,817,049 to Edwards, U.S. Pat. No. 5,823,197 to Edwards, U.S. Pat. No. 5,827,277 to Edwards, U.S. Pat. No. 5,843,077 to Edwards, U.S. Pat. No. 5,871,524 to Knowlton, U.S. Pat. No. 5,873,845 to Cline et al, U.S. Pat. No. 5,873,902 to Sanghvi et al, U.S. Pat. No. 5,879,349 to Edwards, U.S. Pat. No. 5,882,302 to Driscoll, Jr. et al, U.S. Pat. No. 5,895,356 to Andrus et al, U.S. Pat. No. 5,928,169 to Schxc3xa4tzle and U.S. Pat. No. 5,938,608 to Bieger et al.
In particular, focused ultrasound ablation devices used to thermally damage, ablate, coagulate, denature, cauterize, necrotize or destroy a target volume of tissue are exemplified by U.S. Pat. No. Re. 33,590 to Dory, U.S. Pat. No. 4,658,828 to Dory, U.S. Pat. No. 4,807,633 to Fry, U.S. Pat. No. 4,858,613 to Fry et al, U.S. Pat. No. 4,951,653 to Fry et al, U.S. Pat. No. 4,955,365 to Fry et al, U.S. Pat. No. 5,036,855 to Fry et al, U.S. Pat. No. 5,054,470 to Fry et al, U.S. Pat. No. 5,080,101 to Dory, U.S. Pat. No. 5,080,102 to Dory, U.S. Pat. No. 5,117,832 to Sanghvi et al, U.S. Pat. No. 5,143,074 to Dory, U.S. Pat. No. 5,150,711 to Dory, U.S. Pat. No. 5,150,712 to Dory, U.S. Pat. No. 5,295,484 to Marcus et al, U.S. Pat. No. 5,354,258 to Dory, U.S. Pat. No. 5,391,197 to Burdette et al, U.S. Pat. No. 5,431,621 to Dory, U.S. Pat. No. 5,492,126 to Hennige et al, U.S. Pat. No. 5,501,655 to Rolt et al, U.S. Pat. No. 5,520,188 to Hennige et al, U.S. Pat. No. 5,676,692 to Sanghvi et al, U.S. Pat. No. 5,733,315 to Burdette et al, U.S. Pat. No. 5,762,066 to Law et al, U.S. Pat. No. 5,871,524 to Knowlton, U.S. Pat. No. 5,873,845 to Cline et al, U.S. Pat. No. 5,873,902 to Sanghvi et al, U.S. Pat. No. 5,882,302 to Driscoll, Jr. et al, U.S. Pat. No. 5,895,356 to Andrus et al, U.S. Pat. No. 5,928,169 to Schxc3xa4tzle et al and U.S. Pat. No. 5,938,608 to Bieger et al. The focused ultrasound ablation devices are used to ablate various target areas in or on the bodies of patients including the brain, prostate, heart, urethra, blood vessels, deep seated tissue and tumors, liver, kidney, skin, breast, stomach and pancreas.
Ablation of anatomical tissue of the head and/or neck in order to treat various airway related disorders has also been proposed as illustrated by U.S. Pat. No. 5,423,812 to Ellman et al, U.S. Pat. Nos. 5,456,662, 5,514,131, 5,624,439, 5,674,191, 5,707,349, 5,718,702, 5,728,094, 5,730,719, 5,738,114, 5,743,870, 5,743,904, 5,746,224, 5,800,379, 5,800,429, 5,807,308, 5,817,049, 5,823,197, 5,827,277, 5,843,077 and 5,879,349 to Edwards and WO 97/43970. The areas ablated include the soft palate, uvula, tongue, tonsils, adenoids and turbinates. U.S. Pat. No. 5,423,812 relates to electrosurgical stripping of tissue. U.S. Pat. No. 5,456,662, U.S. Pat. No. 5,514,131, U.S. Pat. No. 5,624,439, U.S. Pat. No. 5,674,191, U.S. Pat. No. 5,707,349, U.S. Pat. No. 5,718,702, U.S. Pat. No. 5,728,094, U.S. Pat. No. 5,730,719, U.S. Pat. No. 5,738,114, U.S. Pat. No. 5,743,870, U.S. Pat. No. 5,743,904, U.S. Pat. No. 5,746,224, U.S. Pat. No. 5,800,379, U.S. Pat. No. 5,800,429, U.S. Pat. No. 5,807,308, U.S. Pat. No. 5,817,049, U.S. Pat. No. 5,823,197, U.S. Pat. No. 5,827,277, U.S. Pat. No. 5,843,077, U.S. Pat. No. 5,879,349 and WO97/43970 disclose RF ablation using tissue penetrating electrodes. U.S. Pat. No. 5,707,349, U.S. Pat. No. 5,728,094, U.S. Pat. No. 5,730,719, U.S. Pat. No. 5,738,114, U.S. Pat. No. 5,746,224, U.S. Pat. No. 5,800,379, U.S. Pat. No. 5,800,429, U.S. Pat. No. 5,807,308, U.S. Pat. No. 5,817,049, U.S. Pat. No. 5,823,197, U.S. Pat. No. 5,827,277, U.S. Pat. No. 5,843,077 and U.S. Pat. No. 5,879,349 refer to ultrasound as a possible source of ablative energy.
Prior focused ultrasound ablation devices typically have ultrasound emitting members, commonly including transducers, for emitting ultrasound energy and focusing the ultrasound energy at target areas in anatomical tissue in order to effect thermal ablation at the target areas. Exemplary focused ultrasound ablation devices employing transducers as the ultrasound emitting members thereof are disclosed in U.S. Pat. No. 4,658,828 to Dory, U.S. Pat. Nos. 4,858,613, 4,951,653, 4,955,365, 5,036,855 and 5,054,470 to Fry et al, U.S. Pat. Nos. 5,080,101 and 5,080,102 to Dory, U.S. Pat. No. 5,117,832 to Sanghvi et al, U.S. Pat. Nos. 5,143,074, 5,150,711 and 5,150,712 to Dory, U.S. Pat. No. 5,295484 to Marcus et al, U.S. Pat. No. 5,354,258 to Dory, U.S. Pat. No. 5,391,197 to Burdette et al, U.S. Pat. No. 5,431,621 to Dory, U.S. Pat. No. 5,492,126 to Hennige et al, U.S. Pat. No. 5,501,655 to Rolt et al, U.S. Pat. No. 5,520,188 to Hennige et al, U.S. Pat. No. 5,676,692 to Sanghvi et al, U.S. Pat. No. 5,762,066 to Law et al, U.S. Pat. No. 5,873,845 to Cline et al, U.S. Pat. No. 5,873,902 to Sanghvi et al, U.S. Pat. No. 5,882,302 to Driscoll, Jr. et al, U.S. Pat. No. 5,895,356 to Andrus et al, U.S. Pat. No. 5,928,169 to Schxc3xa4tzle et al, U.S. Pat. No. 5,938,608 to Bieger et al and U.S. Pat. No. Re. 33,590 to Dory.
Some prior focused ultrasound ablation devices employ arrays or pluralities of transducer elements as the ultrasound emitting members, respectively, as represented by U.S. Pat. Nos. 4,658,828, 5,080,101, 5,080,102, 5,143,074, 5,150,712 and U.S. Pat. No. Re. 33,590 to Dory, U.S. Pat. No. 5,391,197 to Burdette et al, U.S. Pat. No. 5,501,655 to Rolt et al, U.S. Pat. No. 5,520,188 to Hennige et al, U.S. Pat. No. 5,928,169 to Schxc3xa4tzle et al and U.S. Pat. No. 5,938,608 to Bieger et al. U.S. Pat. Nos. 4,658,828, 5,080,101, 5,080,102, 5,150,712, 5,501,655, 5,520,188, 5,928,169, 5,938,608 and U.S. Pat. No. Re. 33,590 disclose the transducer elements as being actuated or driven in phase-offset relation to one another in order to change the location at which the ultrasound energy is focused in anatomical tissue.
U.S. Pat. Nos. 5,746,224 and 5,800,429 to Edwards disclose an energy delivery device comprising one or more ring electrodes to which RF energy may be independently delivered to effect thermal ablation of tissue. Ultrasound is merely referred to as a possible source of ablative energy.
In order to enhance the efficacy of focused ultrasound ablation procedures, it would be desirable to customize or tailor lesions to be formed in particular patients for particular procedures. For example, it would be desirable for a single focused ultrasound ablation device to be capable of forming lesions of various sizes and/or configurations or patterns in anatomical tissue including lesions of various irregular or discontinuous patterns. Also, it would be desirable for a focused ultrasound ablation device to be capable of forming a lesion comprising disconnected lesion segments. By providing a focused ultrasound ablation device having the foregoing attributes, optimum lesion characteristics can be selected for particular patients and procedures based on assessments made by surgeons or other medical personnel at the time of surgery. However, prior focused ultrasound ablation devices, as exemplified by the above-mentioned patents, do not provide focused ultrasound emitting members having the foregoing attributes.
Accordingly, it is a primary object of the present invention to overcome the various disadvantages of prior focused ultrasound ablation devices.
It is also an object of the present invention to provide a focused ultrasound ablation device having an ultrasound emitting member capable of forming lesions of various preselected configurations in anatomical tissue.
Another object of the present invention is to provide a focused ultrasound ablation device having an ultrasound emitting member capable of forming a lesion comprising a plurality of disconnected lesion segments in anatomical tissue.
A further object of the present invention is to selectively actuate less than all of a plurality of ultrasound emitting elements of a focused ultrasound emitting member in order to form a lesion of selected size and/or configuration in anatomical tissue.
An additional object of the present invention is to increase the diversity of sizes and/or configurations of lesions capable of being formed in anatomical tissue using focused ultrasound ablation devices.
It is also an object of the present invention to electronically control the actuation of selected ones of a plurality of ultrasound emitting elements of a focused ultrasound emitting member to form a lesion of optimal size and/or configuration in anatomical tissue of a patient.
The present invention also has as an object to provide a multi-array transducer including a plurality of transducer elements that are selectively actuatable to form lesions of various preselected sizes and/or configurations in patients.
Some of the advantages of the present invention are that the outcome of ultrasound ablation procedures in various areas of the body is greatly enhanced, a single focused ultrasound ablation device can optimally be used in various ablation procedures in various areas of the body, anatomical tissue around, between or surrounding the lesion segments can be left undamaged and lesion free, a focused ultrasound emitting member having a particular array of transducer elements can be used to form lesions corresponding in size and/or configuration to the overall size and/or configuration of the array as well as lesions having sizes and/or configurations different from the overall size and/or configuration of the array, the focused ultrasound emitting member can be coupled with a handle for hand-held use and operation thereof, the focused ultrasound ablation device does not have to be customized for use in a specific area of the body, and the focused ultrasound emitting member can be provided in a focused ultrasound ablation device provided as a standardized instrument capable of being used in or on a wide variety of areas of patients"" bodies.
These and other objects, advantages and benefits are realized with the present invention as generally characterized in a focused ultrasound ablation device including an ultrasound emitting member having a plurality of individual ultrasound emitting elements arranged in an array. The ultrasound emitting elements are actuatable to emit ultrasound energy and focus the emitted ultrasound energy at focusing zones, respectively, located a predetermined distance from the ultrasound emitting member. The focusing zones are within a target area in anatomical tissue adjacent which the ultrasound emitting member is placed. The focused ultrasound energy causes the anatomical tissue at the target area to be heated to an ablative temperature to form a lesion. The ultrasound emitting elements are selectively, independently actuatable, allowing selected ones of the ultrasound emitting elements to be actuated to emit ultrasound energy to obtain a lesion of desired or selected size and/or surface configuration. The lesion size and/or surface configuration corresponds to the locations of and/or pattern formed by the ultrasound emitting elements selected for actuation. In this manner, lesion characteristics can be optimally selected for particular patients and particular ablation procedures to be performed. In a preferred embodiment, the ultrasound emitting elements are transducer elements including piezoelectric elements that emit ultrasound energy in response to an electric signal supplied thereto, and selected ones of the transducer elements are selected for actuation by selectively coupling the selected elements to the electrical signal.
A method of thermal ablation of anatomical tissue according to the present invention is generally characterized by the steps of selecting selected ones of a plurality of ultrasound emitting elements, arranged in an array on an ultrasound emitting member, for actuation to emit ultrasound energy in accordance with a desired size and/or configuration of a lesion to be formed in anatomical tissue of a patient, positioning the ultrasound emitting member adjacent or in contact with the anatomical tissue at a location aligned with a target area in the tissue, actuating the selected ones of the ultrasound emitting elements to emit ultrasound energy, focusing the ultrasound energy emitted by the selected ones of the ultrasound emitting elements at focusing zones, respectively, within the target area and heating the tissue of the target area with the focused ultrasound energy to form a lesion having the desired size and/or configuration.